k8s部署-35-k8s中的标签如何使用呢？一文带你了解

k8s部署-35-k8s中的标签如何使用呢？一文带你了解

概念

Label，顾名思义就是标签，在k8s中标签就是一个键值对，key=value，几乎在所有的资源上都可以使用label，非常的灵活：Pod、Deployment、Service、Node上面都可以使用。

其次，同一个资源是可以拥有多个标签的，比如我们的Pod-A，既可以拥有app=tomcat，也可以具有web=nihao的标签，使用上更加方便。

命名规则

Label 必须以字母或数字开头，可以使用字母、数字、连字符、点和下划线，最长63个字符。

作用

我觉得标签的作用是为了统一管理，具有相同特点的pod，可以让其具有同一个label，这样子的话后面管理起来非常方便，也可以指定这个pod在哪个node节点上运行，如果你有特殊需要的话。

实操

首先我们新建一个yaml文件，里面配置上标签；

[root@node1 ~]# cd namespace/[root@node1 namespace]# mkdir label[root@node1 namespace]# cd label/[root@node1 label]# vim label-web-demo.yaml #deployapiVersion: apps/v1kind: Deploymentmetadata: name: tomcat-demospec: selector: matchLabels: app: tomcat-demo replicas: 1 template: metadata: labels: app: tomcat-demo spec: containers: - name: tomcat-demo image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine ports: - containerPort: 8080 resources: requests: memory: 100Mi cpu: 100m limits: memory: 100Mi cpu: 200m---#serviceapiVersion: v1kind: Servicemetadata: name: tomcat-demospec: ports: - port: 80 protocol: TCP targetPort: 8080 selector: app: tomcat-demo---#ingressapiVersion: extensions/v1beta1kind: Ingressmetadata: name: tomcat-demospec: rules: - host: tomcat.yunweijia.com http: paths: - path: backend: serviceName: tomcat-demo servicePort: 80[root@node1 label]# [root@node1 label]# kubectl apply -f label-web-demo.yaml -n dev[root@node1 label]# kubectl get deploy -n dev | grep tomcattomcat-demo 1/1 1 1 33s[root@node1 label]#

上面可以看到运行成功，那么我们再修改下deployment的名字，name: tomcat-demo-yunweijia，别的配置都不修改。如下：

[root@node1 label]# vim label-deploy-web-demo.yaml#deployapiVersion: apps/v1kind: Deploymentmetadata: name: tomcat-demo-yunweijiaspec: selector: matchLabels: app: tomcat-demo replicas: 1 template: metadata: labels: app: tomcat-demo spec: containers: - name: tomcat-demo image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine ports: - containerPort: 8080 resources: requests: memory: 100Mi cpu: 100m limits: memory: 100Mi cpu: 200m---#serviceapiVersion: v1kind: Servicemetadata: name: tomcat-demospec: ports: - port: 80 protocol: TCP targetPort: 8080 selector: app: tomcat-demo---#ingressapiVersion: extensions/v1beta1kind: Ingressmetadata: name: tomcat-demospec: rules: - host: tomcat.yunweijia.com http: paths: - path: backend: serviceName: tomcat-demo servicePort: 80[root@node1 label]# [root@node1 label]# kubectl apply -f label-deploy-web-demo.yaml -n dev[root@node1 label]# kubectl get deploy -n dev | grep tomcattomcat-demo 1/1 1 1 2m51stomcat-demo-yunweijia 1/1 1 1 9s[root@node1 label]#

可以看到，我们运行了两个pod，尽管他们的label是一致的，那是因为我们从最上层就给他分开了，所以互不影响。

实际上不推荐此类方法哈，只是验证下结果，我们给他删除掉；

[root@node1 label]# kubectl delete -f label-deploy-web-demo.yaml -n dev[root@node1 label]# kubectl delete -f label-web-demo.yaml -n dev

标签的IN

什么叫标签的IN呢？其实就是标签的一种IN方法，{key: ceshi, operator: In, values: [dev, test]}，可以判断某个pod是否具有某个标签，如果没有，就会执行失败，如下：

[root@node1 label]# vim label-web-demo.yaml#deployapiVersion: apps/v1kind: Deploymentmetadata: name: tomcat-demo namespace: devspec: selector: matchLabels: app: tomcat-demo matchExpressions: - {key: ceshi, operator: In, values: [dev, test]} replicas: 1 template: metadata: labels: app: tomcat-demo spec: containers: - name: tomcat-demo image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine ports: - containerPort: 8080 resources: requests: memory: 100Mi cpu: 100m limits: memory: 100Mi cpu: 200m---#serviceapiVersion: v1kind: Servicemetadata: name: tomcat-demospec: ports: - port: 80 protocol: TCP targetPort: 8080 selector: app: tomcat-demo---#ingressapiVersion: extensions/v1beta1kind: Ingressmetadata: name: tomcat-demospec: rules: - host: tomcat.yunweijia.com http: paths: - path: backend: serviceName: tomcat-demo servicePort: 80[root@node1 label]# [root@node1 label]# kubectl apply -f label-web-demo.yaml service/tomcat-demo createdWarning: extensions/v1beta1 Ingress is deprecated in v1.14+, unavailable in v1.22+; use networking.k8s.io/v1 Ingressingress.extensions/tomcat-demo createdThe Deployment "tomcat-demo" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app":"tomcat-demo"}: `selector` does not match template `labels`[root@node1 label]#

从上面看报错了，因为我们这个yaml文件中下面的资源没有标签是ceshi，提示只有一个标签是{"app":"tomcat-demo"}，我们新建个label，ceshi: test，再次apply一下看看呢，修改成如下信息：

[root@node1 label]# vim label-web-demo.yaml #deployapiVersion: apps/v1kind: Deploymentmetadata:  name: tomcat-demospec: selector: matchLabels: app: tomcat-demo matchExpressions: - {key: ceshi, operator: In, values: [dev, test]} replicas: 1 template: metadata: labels: app: tomcat-demo ceshi: test spec: containers: - name: tomcat-demo image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine ports: - containerPort: 8080 resources: requests: memory: 100Mi cpu: 100m limits: memory: 100Mi cpu: 200m---#serviceapiVersion: v1kind: Servicemetadata: name: tomcat-demospec: ports: - port: 80 protocol: TCP targetPort: 8080 selector: app: tomcat-demo---#ingressapiVersion: extensions/v1beta1kind: Ingressmetadata: name: tomcat-demospec: rules: - host: tomcat.yunweijia.com http: paths: - path: backend: serviceName: tomcat-demo servicePort: 80[root@node1 label]# [root@node1 label]# kubectl apply -f label-web-demo.yaml deployment.apps/tomcat-demo createdservice/tomcat-demo unchangedingress.extensions/tomcat-demo configured[root@node1 label]#

为什么会有这样的配置呢？这样子是不是可以避免下面的pod乱掉，会强制规定他必须具有某个label呢。查询方式如下：

[root@node1 label]# kubectl get pod -l ceshi=testNAME READY STATUS RESTARTS AGEtomcat-demo-5cb65b749b-sxrzz 1/1 Running 1 20s[root@node1 label]# [root@node1 label]# kubectl get pod -l "ceshi in (dev, test)" -o wideNAME                           READY   STATUS   RESTARTS   AGE     IP             NODE    NOMINATED NODE   READINESS GATEStomcat-demo-5cb65b749b-sxrzz   1/1     Running 5          4m27s   10.200.104.3   node2              [root@node1 label]# [root@node1 label]# kubectl get pod -l "ceshi notin (dev, default)" -o wideNAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESdeploy-springboot-5dbfc55f78-sfqck 1/1 Running 0 90m 10.200.104.6 node2 nginx-ds-q2pjt 1/1 Running 22 15d 10.200.135.32 node3 nginx-ds-zc5qt 1/1 Running 27 21d 10.200.104.2 node2 tomcat-demo-5cb65b749b-sxrzz         1/1     Running            5          4m43s   10.200.104.3    node2              [root@node1 label]#

节点标签

[root@node1 label]# kubectl apply -f label-web-demo.yaml [root@node1 label]# vim label-web-demo.yaml #deployapiVersion: apps/v1kind: Deploymentmetadata: name: tomcat-demo namespace: defaultspec: selector: matchLabels: app: tomcat-demo matchExpressions: - {key: ceshi, operator: In, values: [dev, test]} replicas: 1 template: metadata: labels: app: tomcat-demo ceshi: test spec: containers: - name: tomcat-demo image: registry.cn-hangzhou.aliyuncs.com/liuyi01/tomcat:8.0.51-alpine ports: - containerPort: 8080 resources: requests: memory: 100Mi cpu: 100m limits: memory: 100Mi cpu: 200m nodeSelector: ceshi2: yunweijia ---#serviceapiVersion: v1kind: Servicemetadata: name: tomcat-demospec: ports: - port: 80 protocol: TCP targetPort: 8080 selector: app: tomcat-demo---#ingressapiVersion: extensions/v1beta1kind: Ingressmetadata: name: tomcat-demospec: rules: - host: tomcat.yunweijia.com http: paths: - path: / backend: serviceName: tomcat-demo servicePort: 80[root@node1 label]# [root@node1 label]# kubectl get pod | grep tomcattomcat-demo-8668d869fb-swdsj 0/1 Pending 0 69s[root@node1 label]#

可以看到他是处于一个Pending的状态哈，说明没有找到合适的节点，那么我们给node节点打一个标签再看看呢。

[root@node1 label]# kubectl get nodesNAME STATUS ROLES AGE VERSIONnode2 Ready 22d v1.20.2node3 Ready 22d v1.20.2[root@node1 label]# [root@node1 label]# kubectl label node node3 ceshi2=yunweijianode/node3 labeled[root@node1 label]# kubectl get nodes --show-labelsNAME STATUS ROLES AGE VERSION LABELSnode2 Ready 22d v1.20.2 app=ingress,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node2,kubernetes.io/os=linuxnode3 Ready 22d v1.20.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,ceshi2=yunweijia,kubernetes.io/arch=amd64,kubernetes.io/hostname=node3,kubernetes.io/os=linux[root@node1 label]# kubectl get pod | grep tomcattomcat-demo-8668d869fb-swdsj 1/1 Running 0 3m34s[root@node1 label]# kubectl get pod -o wide| grep tomcattomcat-demo-8668d869fb-swdsj 1/1 Running 1 4m22s 10.200.135.40 node3 [root@node1 label]#

至此，本文结束。